This invention relates to air-to-air refuelling drogue assemblies.
In air-to-air refuelling a tanker aircraft deploys a hose allowing a receiver aircraft to engage with the hose and fuel to be transferred. A drogue assembly used in an air-to-air refuelling system generally comprises a reception coupling for mounting at the end of the hose from the tanker aircraft and for accepting a probe from the receiver aircraft. Mounted to this reception coupling is a drogue, in particular a drogue canopy or parachute, which provides drag as the drogue assembly is pulled through the air by the tanker aircraft. This stabilises the drogue assembly and also provides resistance against which the probe of the receiver aircraft can act when connecting into the reception coupling.
The receiver aircraft may be a helicopter or a conventional fixed wing aircraft. In order to refuel helicopters which can typically refuel at a maximum speed of approximately 130 Knots Equivalent Air Speed (KEAS) a drogue assembly with a high drag at low air speed is required. At higher air speed the drag loads from the helicopter refuelling drogue would be excessive leading to dangerous loads on the hose and therefore a smaller drogue is used for refuelling conventional fixed wing aircraft at higher speeds.
This invention is aimed at preventing excessive loads from being generated in the refuelling hose system in a situation where a drogue may be accidentally used or deployed at a higher air speed than intended. The invention is of particular interest in the case of drogue assemblies which will be used in air-to-air refuelling with high drag at relatively low air speed but is not necessarily exclusively for use in such situations.